test: add more tests for plain objects

Author: pi0

test/utils.test.ts

@@ -1,37 +1,49 @@
+import { describe } from "node:test";
 import { it, expect } from "vitest";
 import { isPlainObject } from "../src/_utils";
 
-it("isPlainObject", () => {
-  expect(isPlainObject(undefined)).toBe(false);
-  expect(isPlainObject(0)).toBe(false);
-  expect(isPlainObject(0n)).toBe(false);
-  expect(isPlainObject("")).toBe(false);
-  expect(isPlainObject(true)).toBe(false);
-  expect(isPlainObject(Symbol(""))).toBe(false);
-  expect(isPlainObject(() => {})).toBe(false);
-  expect(isPlainObject(function namedFunc() {})).toBe(false);
-  expect(isPlainObject(null)).toBe(false);
-  expect(isPlainObject({})).toBe(true);
-  expect(isPlainObject(Math)).toBe(false);
-  expect(isPlainObject(new Set([]))).toBe(false);
-  expect(isPlainObject(new ArrayBuffer(0))).toBe(false);
-  expect(isPlainObject(Promise.resolve())).toBe(false);
-  expect(isPlainObject(Object.create(null))).toBe(true);
-  expect(isPlainObject(new Intl.Locale("en"))).toBe(false);
-  // eslint-disable-next-line no-new-object
-  expect(isPlainObject(new Object({ prop: true }))).toBe(true);
-  expect(isPlainObject(new (class Class {})())).toBe(false);
-  expect(isPlainObject([])).toBe(false);
-  expect(isPlainObject(/regexp/)).toBe(false);
-  expect(isPlainObject(new Error("test"))).toBe(false);
-  expect(isPlainObject(new Date())).toBe(false);
-  expect(
-    isPlainObject(
-      (function () {
-        // eslint-disable-next-line prefer-rest-params
-        return arguments;
-      })(),
-    ),
-  ).toBe(false);
-  // expect(isPlainObject(new Proxy({}, {}))).toBe(false); // TODO
+describe("isPlainObject", () => {
+  it("plain objects", () => {
+    expect(isPlainObject({})).toBe(true);
+    expect(isPlainObject({ prop: true })).toBe(true);
+    expect(isPlainObject({ constructor: true })).toBe(true);
+    expect(isPlainObject({ __proto__: true })).toBe(true);
+    expect(isPlainObject(new Proxy({}, {}))).toBe(true);
+  });
+
+  it("non plain objects", () => {
+    expect(isPlainObject(undefined)).toBe(false);
+    expect(isPlainObject(0)).toBe(false);
+    expect(isPlainObject(0n)).toBe(false);
+    expect(isPlainObject("")).toBe(false);
+    expect(isPlainObject(true)).toBe(false);
+    expect(isPlainObject(Symbol(""))).toBe(false);
+    expect(isPlainObject(() => {})).toBe(false);
+    expect(isPlainObject(function namedFunc() {})).toBe(false);
+    expect(isPlainObject(null)).toBe(false);
+    expect(isPlainObject({})).toBe(true);
+    expect(isPlainObject(Math)).toBe(false);
+    expect(isPlainObject(new Set([]))).toBe(false);
+    expect(isPlainObject(new ArrayBuffer(0))).toBe(false);
+    expect(isPlainObject(Promise.resolve())).toBe(false);
+    expect(isPlainObject(Object.create(null))).toBe(true);
+    expect(isPlainObject(new Intl.Locale("en"))).toBe(false);
+    // eslint-disable-next-line no-new-object
+    expect(isPlainObject(new Object({ prop: true }))).toBe(true);
+    expect(isPlainObject(new (class Class {})())).toBe(false);
+    expect(isPlainObject([])).toBe(false);
+    expect(isPlainObject(/regexp/)).toBe(false);
+    expect(isPlainObject(new Error("test"))).toBe(false);
+    expect(isPlainObject(new Date())).toBe(false);
+    expect(
+      isPlainObject(
+        (function () {
+          // eslint-disable-next-line prefer-rest-params
+          return arguments;
+        })(),
+      ),
+    ).toBe(false);
+    expect(isPlainObject({ [Symbol.toStringTag]: true })).toBe(false);
+    expect(isPlainObject({ [Symbol.iterator]: true })).toBe(false);
+  });
 });